Preferred name: Sirex ermak
Authority: (Semenov-Tian-Shanskij)
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Hymenoptera: Siricidae
Other scientific names: Paururus ermak Semenov-Tian-Shanskij
Common names in English: blue-black horntail, blue-black woodwasp
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Notes on taxonomy and nomenclature EPPO Categorization: A2 list
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EPPO Code: SIRXER

Sirex ermak develops on coniferous trees from the family Pinaceae. The preferred hosts are Larix species (e.g. L. sibirica, L. gmelinii, L. dahurica) (Gussakovskij, 1935; Byalaya, 1966; Mamaev & Kravchenko, 1974; iitasaari, 1988; Orlinski, 2006; Agafonova & Antonov, 2014). Species of Picea, Abies, Pinus are also suitable hosts (Pavlovskij & Shtakelberg, 1955; Stroganova, 1963, 1968; Byalaya, 1966; Tkacz et al., 1991; Vorontsov, 1981; Sundukov & Lelei, 2012; Kostyunin, 2015; Sundukov, 2017). S. ermak can be found on coniferous species from different genera in the same region (Stroganova, 1968). Nevertheless, its abundance on certain hosts seems to show some geographical linkage. In the European part of Russia, it mainly attacks Picea obovata (Sundukov & Lelei, 2012). In Western Siberia (Tomsk Oblast, Kemerovo Oblast), it was found mostly on Abies sibirica (Stroganova, 1963; Krivets & Chemodanov, 2005). In Eastern Siberia in the Baikal region (Irkutsk Oblast and Buyratia Republic), S. ermak was documented exclusively on Larix spp. (Agafonova & Antonov, 2014), whereas in the Russian Far East, it was recorded as one of the notable pest of pines, Pinus sylvestris in Zabaykalsky Krai (Talman, 1948), Pinus koraiensis and spruces (Picea ajanensis, Picea koraiensis) in Primorsky Krai (Ivlev & Kononov, 1974). In China, it was documented as a pest of Picea species (P. obovata, P. crassifolia, P. schrenkiana) (Gao & Shi, 2021).

Host list: Abies holophylla, Abies nephrolepis, Abies sibirica, Abies sp., Larix gmelinii var. gmelinii, Larix gmelinii, Larix sibirica, Larix sp., Picea crassifolia, Picea jezoensis subsp. jezoensis, Picea jezoensis, Picea koraiensis, Picea obovata, Picea schrenkiana, Picea sp., Pinus koraiensis, Pinus sibirica, Pinus sp., Pinus sylvestris var. mongholica, Pinus sylvestris

Sirex ermak is a Central-Eastern Palearctic species. It is found in forest-steppes, taigas, floodplains and subalpine forests, and woodlands (Agafonova & Antonov, 2014; Kostyunin, 2015). In the mountains, S. ermak has been recorded up to the forest line frontier (Byalaya, 1966).

S. ermak is distributed over a wide area in Russia. Its main range lays in the Asian part of the country, i.e. in Western and Eastern Siberia and the Russian Far East, including Kamchatka, Sakhalin, and southern Kuril Islands (Gussakovskij, 1935; Talman, 1948; Pavlovskij & Shtakelberg, 1955; Stroganova, 1968; Mamaev & Kravchenko, 1974; Ivlev & Kononov, 1974; Vorontsov, 1981; Zhelochovtsev & Zinovjev, 1996; Orlinski, 2006; Sundukov & Lelei, 2012; Sundukov, 2013, 2017; Kostyunin, 2015). The most western findings of the species have been made in the European part of the country, in central regions, Kaliningrad and Moscow Oblasts according to Zhelohovtsev et al. (1988) and Zhelochovtsev & Zinovjev (1996). Other authors (e.g. Sundukov & Lelei, 2012; Sundukov, 2017) cited these records from the studies of Zhelochovtsev (Yu.N. Sundukov, Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch of the Russian Academy of Sciences: personal communication, Vladivostok, Russia, 2023). It remains unclear whether S. ermak is native or introduced in these regions. Furthermore, its establishment in the European part of Russia still needs to be confirmed by further studies. The recent record of S. ermak in Saratov Oblast, the region on south-west of the European part of Russia, in 858 km from Moscow (Volodchenko, 2019) is erroneous and should be attributed to Sirex juvencus (L.) (A.N. Volodchenko, Saratov State University, Saratov, Russia: personal communication, 2023).

In addition to Russia, the species is also known from Eastern Kazakhstan (Sundukov, 2017; Tleppaeva et al., 2017), Northern Mongolia (Zhelohovtsev et al., 1988; Orlinski, 2006; Sundukov & Lelei, 2012; Kostyunin, 2015; Sundukov, 2017), North-Eastern China (Zhelohovtsev et al., 1988; Sundukov & Lelei, 2012; Sundukov, 2017; Gao & Shi, 2021), and Korea (Kostyunin, 2015).

EPPO Region: Kazakhstan, Russia (Central Russia, Eastern Siberia, Far East, Western Siberia)
Asia: China (Qinghai), Kazakhstan, Korea Dem. People's Republic, Korea, Republic, Mongolia

In the Asian part of Russia, the flight period of S. ermak is from July/August to September (Stroganova, 1963, 1968; Byalaya, 1966; Verzhutskij, 1973; Kostyunin, 2015). During the day, intensive flight is observed in the afternoon from 15:00 to 18:00. At other times, adults usually stay in the shadow and in humid sites of the forest (Stroganova, 1963, 1968). Byalaya (1966) observed that S. ermak adults prefer well insulated and warm spots in the forest. Adults do not need additional maturation feeding and can survive up to 14 days (Byalaya, 1966). Soon after emergence, females are ready to mate, and they lay eggs the day after copulation. They insert their flexible ovipositors deeply into the wood of the main trunk (e.g. with a diameter of 15-30 cm with medium or thick bark) and lay eggs (Byalaya, 1966; Stroganova, 1968). A female lays one egg (occasionally two) in each hole; females carry from 115 eggs (small-sized females) to 374 eggs (larger individuals) (Byalaya, 1966). While ovipositing, females infect trees with spores of symbiotic wood rotting basidiomycete fungi (Amylostereum spp.), which are usually present in special organs called ‘mycangiae’ that are situated at the base of the ovipositor (Byalaya, 1966). Neonate larvae usually hatch in 42–28 days (Byalaya, 1966). They make galleries in wood, and fill them with fine sawdust. The total length of larval galleries varies from 5 to 25 cm, with a depth ranging from 0.5 to 6 cm beneath the wood surface (Byalaya, 1966; Verzhutskij, 1973). Larval development takes 1.5–2 years (Stroganova, 1963). Pupation usually occurs in June. Larvae prepare pupation cells deep in the wood (3–4 cm beneath the surface). Pupae develop within 16-25 days; the total degree-days required for pupal development lies between 280°C and 416°C (Byalaya, 1966). Emergence holes are free from sawdust. The life cycle of S. ermak usually takes 2 years, rarely 3-4 years (Stroganova, 1963, 1968; Byalaya, 1966; Verzhutskij, 1973).

Symptoms

S. ermak causes tree dieback, which is easily detected by the observation of wilting needles. Emergence holes in trunks are signs of the presence of the pest (Stroganova, 1968); these are most often situated in the lower part of the tree crown (Ivlev & Kononov, 1974). S. ermak often attacks trees together with Serropalpus barbatus (Coleoptera: Melandryidae), a beetle widely spread in Europe and Asia, which can be used as indicator of the presence of S. ermak (Stroganova, 1968). It is not unusual to see S. ermak adults resting on tree trunks; they can be found in the lower part of the tree crowns (Stroganova, 1968).

Morphology

Eggs

The egg of S. ermak is white, oval-elongated, with a semi-transparent cover (Stroganova, 1968).

Larva

Larvae of S. ermak are white, cylindrical, 15–28 mm long, slightly S-form curved, with a slightly sclerotized round yellowish head (Stroganova, 1968; Byalaya, 1966). The head is covered with dense bristles. Abdominal legs are not developed. Antennae with 4–9 bristles. On the anal tergite, there is a longitudinal fissure between two small protuberances. The lateral part of the anal segment is half-covered with bristles. A sclerotized thorn is situated on the top of the abdomen (Stroganova, 1963; Verzhutskij, 1973; Mamaev & Kravchenko, 1974; Vorontsov, 1981). Larvae moult three times (Byalaya, 1966).

Pupa

Pupae of S. ermak are free, elongated, 18–25 mm long, tapered towards the rear, with a small sclerotized thorn at the top of the abdomen (Stroganova, 1968; Byalaya, 1966).

Adult

The adult of S. ermak is a large thick-waisted cylindrical insect with a black body and black round head with metallic blue reflections on the back part, covered by long dense hairs (Stroganova, 1963, 1968; Verzhutskij, 1973). The thorax is black with metallic blue reflections, wrinkled and covered by long dense hairs. The front angles of the pronotum are acute, the back end of the pronotum is rounded. Mesopleurae are bright and sparsely punctuated. The abdomen is slightly wrinkled; the 1st tergite has a deep transversal fissure. In females, the abdomen is uniformly black with a blue shade, whereas in males the 4^th-6^th segments of the abdomen can be reddish (Gussakovskij, 1935), especially in the populations from Eastern Siberia (Stroganova, 1963; Verzhutskij, 1973). Antennae are black (in females), or brownish or yellowish at the first half from the base (in males), relatively thin, with 20 segments; the 1^st segment is a little widened and flattened at the top (Byalaya, 1966; Stroganova, 1968; Verzhutskij, 1973). Wings are transparent slightly darkened at the top (especially close to the pterostigma), with a grey edge; the wing veins are dark brown. In females, legs are black with metallic blue reflections, except apexes of femora and bases of tibiae and tarsi, which are reddish-brown (Gussakovskij, 1935; Verzhutskij, 1973). Femora are widened, and back tibiae are narrowed in the middle. Females have a stinger-like ovipositor, nearly as long as the abdomen, that extends straight back when not in use (Stroganova, 1968). The following ratios have been determined: length of forewing/ ovipositor: 1–1.38 (Stroganova, 1968), distance between ridges 4 and 5/diameter of ovipositor: 2.20–2.30, distance between ridges 9 and 10/ diameter of ovipositor: 1.75–1.85 (Viitasaari, 1988). These values were suggested for the species identification (Viitasaari, 1988). The female of S. ermak is 13–25 mm long; the male is 15–17 mm long (Stroganova, 1963, 1968; Vorontsov, 1981).

Detection and inspection methods

As for other Sirex spp., visual inspections can be used to detect the presence of S. ermak in tree stands (Maslov et al., 1988). A sign of colonization is the presence of round adult exit holes in the tree trunks of coniferous species (Pinaceae). On weakened trees, bark can be removed in areas where adult exit holes are present to find the characteristic galleries inside the wood and immature insects. Larvae are difficult to distinguish between different Sirex species, therefore DNA barcoding seems to be the only option to reliably identify the species on larval stage or insect remnants found in the galleries. At present, 7 DNA barcodes of S. ermak are available for comparison in BOLD (Barcode of Life Data System), including the DNA barcodes obtained for 4 specimens of S. ermak, i.e. for 2 specimens (including the syntype) stored at the Zoological Institute RAS (Saint Petersburg, Russia) and 2 specimens from Sukachev Institute of Forest SB RAS (Krasnoyarsk). These DNA barcodes can be used for the species identification. No pheromone monitoring system has been developed so far. However, the attractants used for wood-boring insects in the USA, containing 1S-alpha-pinene and 1S-beta-pinene (Coyle et al., 2012), or the mix of ethyl alcohol, alpha-pinene, ipsenol, ipsdienol, and 3-carene (Costello et al., 2008) were shown to be attractive for the related species, S. juvencus. However, their efficiency to attract S. ermak has not been explored yet.

Adult can spread by flying. However, no data on the distance which S. ermak adults can cover is available from published sources. Because S. ermak may be hidden deep in the wood for long periods (taking into account its 2-year life cycle, exceptionally 3-4 years), it is difficult to detect the pest in the wood, and, thus, it can easily be transported with untreated wood moving in trade, including dunnage and wood packaging material. It is unlikely, however, that it can be transported with plants for planting, since it does not attack seedlings or small trees, which constitute planting material. Potential pathways are wood, dunnage, and wood packaging material (Madsen et al., 2014).

Economic impact

S. ermak is an important pest of Larix in Siberia and the Far East, and is also known to attack other conifers (Abies, Picea, Pinus). It colonizes mainly stressed trees (usually after 2 years of stress) (Stroganova, 1963). In Siberia, it often attacks weakened forest stands (in particular, Larix sibirica stands) after defoliation by Dendrolimus sibiricus, leading to tree decline (Stroganova, 1963; Byalaya, 1966; Verzhutskij, 1973). Following D. sibiricus outbreaks, mass decline of larch due to colonization by S. ermak may be observed within the decade following the beginning of the D. sibiricus outbreak (Byalaya, 1966). In China, S. ermak often co-occurs with other horntails, such as Sirex juvencus, S. dux, Urocerus gigas, and Xeris spectrum, infesting weakened or declining spruce stands and, thus, accelerating tree death (Gao & Shi, 2021). S. ermak can also infest cut trees and logs with bark in cutting areas and warehouses, rendering them unusable (Stroganova, 1963, 1968; Vorontsov, 1981; Kostyunin, 2015). Furthermore, it can colonize logging residues (Vorontsov, 1981; Kostyunin, 2015). Despite the fact that the galleries of S. ermak larvae in wood are relatively short, dead trees cannot be used as commercial timber, because in addition to mechanical damage, such trees suffer from fungal infection. Ovipositing females infect wood with fungal spores (in particular, basidiomycetes, ascomycetes). These fungi develop rapidly spreading radially and growing deep in the wood (Byalaya, 1966; Maslov et al., 1988). Two or three years after the first attack of S. ermak, wood becomes unusable because of fungal infection (Pavlovskij & Shtakelberg, 1955; Stroganova, 1965, 1968; Byalaya, 1966; Verzhutskij, 1973).

Control

As for other Sirex spp., control measures include sylvicultural and sanitary measures (improving the resistance of forests, cutting and elimination infested trees, use of trap-trees) (Maslov et al., 1988), treatments with chemical and biological products. Natural enemies seem to play an important role in the control of S. ermak populations, especially the hymenopterous parasitoids (Ibalia leucospoides, Rhyssa amoena, Rhyssa persuasoria, Rhyssa superba, and Xylonomus sp.), the parasitoid fly Erinna cincta, and certain birds (e.g. Dendrocopos major, D. minor,  Dryobates sp., Dryocopus sp., Picus sp., Picoides tridactylus) (Byalaya, 1966; Kolomiets & Bogdanova, 1979). Nevertheless, natural enemies are not widely used against S. ermak.

Phytosanitary risk

S. ermak is considered as a serious pest of Larix and other conifers (Abies, Picea, Pinus) in the area of its present distribution (Stroganova, 1968). The range of climatic conditions in the area of origin and present distribution of S. ermak is large, and it is likely to establish in almost all coniferous forests of the EPPO region where any European conifer tree species (Larix, Abies, Picea, Pinus) are found. Northern and central parts of Europe are especially endangered (Orlinski, 2006).

Recommended phytosanitary measures, for wood of host plant species, could include the following: origin from a pest-free area, or debarking, or freedom from any signs the pest, i.e. the adult exit holes and larval galleries, or heat treatment, or other appropriate treatment. Wood packaging material, including dunnage, should respect ISPM no. 15 (FAO, 2019).

Agafonova TA & Antonov IA (2014) [Catalog of xylophagous insects of coniferous species of Baikal Siberia and the Northern Amur region: based on stock materials of the museum ‘Terrestrial Ecosystems of Baikal Siberia’.] SIFIBR SB RAS. Publishing house of the Institute of Geography named after V.B. Sochavy SB RAS, Irkutsk (RU), 216 pp (in Russian).

Benson RB (1963) A character gradient in Sirex juvencus. Entomologist’s Monthly Magazine 98, 252–253.

Byalaya IV (1966) [Family Siricidae – Horntails]. In: Pests of Siberian Larch. Rozhkov AS (Ed). Nauka, Moscow (RU), pp. 158–163 (in Russian).

Costello SL, Negron JF & Jacobi WR (2008) Traps and attractants for wood-boring insects in ponderosa pine stands in the black hills, South Dakota. Journal of Economic Entomology 101, 409–420.

Coyle DR, Pfammatter JA, Journey AM, Pahs TL Cervenka VJ & Koch RL (2012) Community composition and phenology of native Siricidae (Hymenoptera) attracted to semiochemicals in Minnesota. Environmental Entomology 41, 91–97.

FAO (2019) ISPM 15. Regulation of wood packaging material in international trade. FAO, Rome, 24 pp. https://www.ippc.int/en/publications/640/

Gao T & Shi J (2021) The potential global distribution of Sirex juvencus (Hymenoptera: Siricidae) under near current and future climatic conditions as predicted by the maximum entropy model. Insects 12, 1–21. https://doi.org/10.3390/insects12030222

Gussakovskij VV (1935) [Fauna of USSR. Insects. Hymenoptera. Siricidae and Tenthredinidae.] (eds Zernov CA, Shtakelberg AA). The Edition of the Academy of Sciences of USSR, Leningrad (RU), No. 1 (in Russian).

Ivlev LA & Kononov DG (1974) [Insects – the xylophages of pines in the Primorsky Territory] In: Insects – wood destroyers in forest biocenoses of Southern Primorye. Nauka, Moscow (RU), pp. 41–49 (in Russian).

Kolomiets NG & Bogdanova DA (1979) [Parasitoids and predators of xylophages in Siberia.] Nauka, Novosibirsk (RU), 280 pp (in Russian).

Kostyunin AV (2015) Fauna and ecology of sawflies and horntails (Hymenoptera, Symphyta) of the southeastern of Western Siberia. Candidate thesis. Novosibirsk, 261 pp (in Russian).

Krivets SA & Chemodanov AV (2005) Insect pests of forests in the Tomsk region. Entomological research in Siberia. Krasnoyarsk: SIF SB RAS, Vol. 4. pp. 98–118.

Madsen CL, Dahl CM, Thirslund KB, Grousset F, Johannsen VK & Ravn HP (2014) Pathways for non-native species in Denmark. Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, 131 pp.

Mamaev BM & Kravchenko MA (1974) [Larvae of horntails (Hymenoptera, Siricidae).] In: Insects – wood destroyers in forest biocenoses of Southern Primorye. Nauka, Moscow (RU), pp. 74–85 (in Russian).

Maslov AD, Vedernikov NM, Andreeva GI, Zubov PA, Krangauz RA, Lyzshenko LI & Pavlinov NP (1988) [Protecting forests from pests and diseases: a handbook.] (ed. Maslov AD), Agropromizdat, Moscow (RU), 2^nd edition, revised and expanded, 414 pp (in Russian).

Orlinski AD (2006) Outcomes of the EPPO project on quarantine pests for forestry. EPPO Bulletin 36, 497–511.

Pavlovskij EN & Shtakelberg AA (1955) [Guide to Forest Pests.] Izdatel’stvo Akademii Nauk SSSR, Moscow–Leningrad (RU), 1097 pp (in Russian).

Stroganova VK (1963) [Horntails (Hymenoptera, Siricidae) of Western Siberia.] In: Proceedings of Biological Institute, Novosibirsk (RU), Vol. 10, pp. 24–42 (in Russian).

Stroganova VK (1968) [Horntails of Siberia.] Nauka, Moscow (RU), 148 pp (in Russian).

Sundukov YuN (2013) The annotated bibliography on taxonomy and fauna of Symphyta (Hymenoptera) the Russian Far East. Part 4: U – Z and publications in Cyrillics. Amurian zoological journal 4, 449–459 (in Russian).

Sundukov YuN (2017) [Siricidae.] In: Annotated catalogue of the Hymenoptera of Russia. Vol. I. Symphyta and Apocrita: Aculeata. (eds Belokobylskij SA, Lelej AS). Proceedings of the Zoological Institute RAS, Supplement 6, 2017, pp. 112–114 (in Russian).

Sundukov YuN & Lelei AS (2012) [Family Siricidae.] In: Annotated catalogue of the insects of Russian Far East. Volume I. Hymenoptera. (ed. Lelei AS), Dalnauka, Vladivostok (RU), pp. 112–113 (in Russian).

Talman PN (1948) About wood wasps Sirex gigas L. and Xanthosirex tardigradus Ced. (Hymenoptera, Siricidae). Entomologicheskoe Obozrenie 1–2, 82–87 (in Russian).

Tkacz B et al. (1991) Pest Risk Assessment on the importation of larch from Siberia and the Soviet Far East. United States Department of Agriculture. Forest Service Miscellaneous Publication, No. 1495, 263 pp.

Tleppaeva AM, Kadyrbekov RKh, Kolov SV & Zlatanov BV (2017) Insects-xylophages of trees and shrubs of the mountains of the Almaty region. TOO 378, Almaty (KAZ), 196 pp (in Russian).

Verzhutskij BN (1973) [Taxonomic keys for larvae of horntails and sawflies of Siberia and the Far East.] Nauka, Moscow (RU), 140 pp (in Russian).

Volodchenko AP (2019) [Xylophagous pests of pine forests of Balashovsky forestry, Saratov region] In: Biodiversity and anthropogenic transformation of natural ecosystems, the materials of the All-Russian scientific and practical conference dedicated to the 110th anniversary of Saratov University and the 25th anniversary of the Voroninsky State Nature Reserve. Saratov National Research State University named after N.G. Chernyshevsky. Saratov, 6–8 June, 2019, pp 53–55 (in Russian).

Viitasaari M (1988) New methods for identification of woodwasps (Siricidae) with notes on Euro-Siberian species of Sirex. In: Connections between Entomofauna of Northern Europe and Siberia, Institute of Zoology of the Academy of Sciences of the USSR, Leningrad (RU), pp. 3–12 (in Russian, English).

Vorontsov AI (1981) [Insects – wood destroyers]. Lesnaya Promishlennost, Moscow (RU), 176 pp (in Russian).

Zhelochovtsev AN & Zinovjev AG (1996) A list of the sawflies and horntails (Hymenoptera, Symphyta) of thе fauna of Russia and adjacent territories. II. Entomologicheskoe Obozrenie LXXV, 2, 357–379 (in Russian).

Zhelohovtsev AN, Tobias VI & Kozlov MA (1988) [Family Siricidae] In: Key to insects of the European part of the USSR. Hymenoptera. (ed. Skarlato OA). Vol. 111, 6^th part. Nauka, Leningrad (RU), pp 226–228 (in Russian).

This datasheet was extensively revised in 2024 by Dr. Natalia Kirichenko (Sukachev Institute of Forest of the Siberian Branch of the Russian Academy of Sciences, Federal Research Center ‘Krasnoyarsk Science Center SB RAS’ and All-Russian Plant Quarantine Center, Krasnoyarsk branch, Krasnoyarsk, Russia and Stanislav Gomboc (Slovenia). Their valuable contribution is gratefully acknowledged.

EPPO (2024) Sirex ermak. EPPO datasheets on pests recommended for regulation. https://gd.eppo.int (accessed 2024-04-27)

This datasheet was first published in the EPPO Bulletin in 2005 and revised in 2024. It is now maintained in an electronic format in the EPPO Global Database. The sections on 'Identity', ‘Hosts’, and 'Geographical distribution' are automatically updated from the database. For other sections, the date of last revision is indicated on the right.

EPPO (2005) Sirex ermak. Datasheets on pests recommended for regulation. EPPO Bulletin 35(3), 453-455. https://doi.org/10.1111/j.1365-2338.2005.00853.x